The purpose of this investigation is to continue our characterization of the structural domains of the higher and lower molecular weight human salivary mucins. Structural comparisons of these molecules will be made between two groups: (a) caries susceptible versus caries resistant subjects and (b) individuals with cystic fibrosis versus normals. The proposed studies wil utilize basic biochemical methods in carbohydrate and protein chemistry and recombinant DNA technology. In particular, techniques of periodate oxidation, methylation analyses by GC/mass spectroscopy, exoglycosidase digestion, and NMR spectroscopy will be used to delineate oligosaccharide structures. Automated peptide sequencing and recombinant DNA techniques will be used to define the peptide sequences. The information to be obtained could ultimately provide an insight regarding (a) the role of salivary mucins in oral clearance and adherence phenomena; (b) the mechanisms by which the host can intrinsically regulate resistance to dental caries; and (c) the changes which occur in mucins in exocrine secretions in cystic fibrosis. Such knowledge could ultimately lead to modalities useful in both the prevention and treatment of diseases manifest in the oral cavity.